使用Java Socket实现一个猜数字小游戏

import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Random;
import java.util.Scanner;

public class ServerDemo {
 private int flag;

 public void server() throws IOException {
  //创建一个服务器
  System.out.println("服务端启动，等待客户端连接。。。");
  PrintWriter out = null;
  Scanner getClient = null;
  ServerSocket server = null;
  Socket client = null;
  this.setFlag();
  try {
   server = new ServerSocket(6666);
   //创建一个接收连接客户端的对象
   client = server.accept();
   System.out.println(client.getInetAddress() + " 已成功连接到此台服务器上。");
   //字符输出流
   out = new PrintWriter(client.getOutputStream()); //向客户端发送数据
   out.println("欢迎来到猜数字小游戏（1-100）！！！");
   out.flush();//将缓冲流中的数据全部输出
   getClient = new Scanner(client.getInputStream()); //接收客户端发送的数据
   //阻塞等待客户端发送消息过来
   while (getClient.hasNextLine()) {
    String returnMsg = null;
    String tmp = getClient.nextLine();
    if ("e".equals(tmp)) {
     break;
    } else if ("c".equals(tmp)) {
     returnMsg = "欢迎来到新一轮的猜数字小游戏（1-100）！！！";
     this.setFlag();
    } else {
     int clientInput = Integer.parseInt(tmp);

     if (clientInput > flag) {
      returnMsg = "你输入的数字大了！！！";
     } else if (clientInput < flag) {
      returnMsg = "你输入的数字小了！！！";
     } else {
      returnMsg = "恭喜你，猜中了！！！继续（输入c）,退出（输入e）";
     }
    }
    out.println(returnMsg); //向客户端发送数据
    out.flush();
   }
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } finally {
   out.close();
   getClient.close();
   server.close();
  }
 }

 // 生成随机数字
 public void setFlag() {
  Random r = new Random();
  flag = r.nextInt(100);
  System.out.println("猜数字小游戏答案：flag = " + flag);
 }

 public static void main(String[] args) throws IOException {
  new ServerDemo().server();
 }
}

import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

public class ClientDemo {

 public void client() throws IOException {
  System.out.println("正在向服务器请求连接。。。");
  Socket client = null;
  Scanner getKey = null;
  Scanner getServer = null;
  PrintWriter out = null;
  try {
   client = new Socket("127.0.0.1", 6666);
   getServer = new Scanner(client.getInputStream());
   System.out.println(getServer.nextLine());
   out = new PrintWriter(client.getOutputStream());
   System.out.print("请输入数字：");
   //先读取键盘录入方可向服务端发送消息
   getKey = new Scanner(System.in);
   while (getKey.hasNextLine()) {
    //写到服务端的的控制台
    out.println(getKey.nextLine());
    out.flush();
    try {
     System.out.println("提示消息：" + getServer.nextLine());
     System.out.print("请输入数字：");
    } catch (Exception e) {
     System.out.print("游戏结束！！！");
     break;
    }
    //阻塞等待接收服务端的消息
   }
  } catch (Exception e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } finally {
   getKey.close();
   getServer.close();
   out.close();
   client.close();
  }

 }

 public static void main(String[] args) throws IOException {
  new ClientDemo().client();
 }
}